The hardening methods of solid surfaces and lubricants have been developed to allow two contacting solid materials to slide with low wearing at a low friction and to elongate the service lives of machines, apparatuses, etc. In particular, in the field of office automation equipment, downsizing is strongly sought, such that very precision mechanisms are employed in sliding parts. Newly developing machines, in which precision parts that will continuously or discontinuously move in a sliding manner under a wide variety of conditions, should further reduce friction and wearing when the sliding movement starts, continues and stops, in comparison with conventional precision parts, so as to decrease the load on motors, etc.
In conventional protective lubrication systems, a surface layer, which is hard and difficult to wear, is formed on a sliding part, and semi-solid or liquid lubricants such as greases or oils are used as lubricants. However, for precision parts which require smoothness of contacting surfaces, no lubricant has been known, which allows two solid materials to slide with low wearing at a low friction irrespective of a high or low sliding rate, and at a high or low load, and it is still impossible to overcome problems such as starting malfunctions or the accidental and abrupt increase of a friction force.
For example, in the case of ferromagnetic metal thin film type magnetic recording media comprising a non-magnetic substrate and the thin film of a ferromagnetic metal or its alloy, which is formed on the substrate by vacuum deposition and the like, the coercive force of a magnetic layer can be easily increased, and the thickness of a magnetic layer can be decreased in comparison with coating type magnetic recording media, and thus they have a high recording density. The ferromagnetic metal thin film type magnetic recording media do not use binder resins which impart toughness to the media, and the ferromagnetic metal layer or a protective film, which is usually formed on the ferromagnetic metal layer, posseses good surface smoothness. Thus, the magnetic recording medium sticks to a magnetic head, and the coefficient of friction increases. Accordingly, such media are easily abraded or damaged, and have inferior durability and running properties.
To cope with such problems, many patent applications, for example, JP-A-3-254419, JP-A-4-270243, JP-A-6-293703, JP-A-7-118204, JP-A-7-216375, JP-A-7-225941, JP-A-7-324061, etc., propose the use of various lubricants such as perfluoropolyether lubricants (e.g. "FOMBLIN Z DOL" and "FOMBLIN AM 2001" both available from Ausimont), carboxylic acid lubricants, partially fluorinated ester lubricants, and the like, and discuss the improvement of durability and running properties by the presence of such lubricants on ferromagnetic metal thin films.
However, the use of such lubricants cannot solve encountered problems, such as dropouts caused by the contamination of magnetic heads or defects on the surfaces of recording media formed by sliding contact, or the inferior durability or running properties under high humidity circumstances.